Engine Ignition - V6 S/C 3.0L Petrol (G1903641): Operation

The ignition coils are supplied with electrical power from the PCM relay in the EJB. The PCM controls the operation of the PCM relay.

The PCM sends a separate signal to each ignition coil to trigger the power stage switching. The PCM calculates the dwell time from the battery voltage and engine speed, to ensure a constant energy level is produced in the secondary coil each time the power stage is switched. This ensures sufficient spark energy is available without excessive primary current flow, which avoids overheating and damage to the ignition coils.

The PCM calculates the ignition timing for individual cylinders from:

• Engine speed from the Crankshaft Position (CKP) sensor.
• Camshaft position from exhaust and intake Camshaft Position (CMP) sensors.
• Engine load.
• Engine temperature.
• The knock control function.
• The shift control function.
• The idle speed control function.